Screening in medicine is a strategy used to identify unrecognised conditions or risk factors in apparently healthy individuals. It is performed on individuals who do not yet show symptoms of a particular disease, with the aim of detecting potential health disorders at an early stage. This distinguishes it from diagnostic testing, which is performed when a person already has symptoms and a disease is suspected.

The primary goals of screening are multifaceted and centered around improving public health outcomes:

1. Early Detection of Disease: This is arguably the most fundamental goal. Screening aims to find a disease in its preclinical or latent stage, before symptoms become apparent. Many serious conditions, such as certain cancers (e.g., breast, cervical, colorectal), diabetes, and hypertension, are easier to treat and more manageable when detected early. Early detection can significantly increase the chances of successful treatment and potentially lead to a cure.
2. Prevention of Disease Progression and Complications: By identifying a disease or a significant risk factor early, interventions can be implemented to prevent the condition from worsening or to delay its onset. For example, detecting prediabetes through screening allows for lifestyle changes that can prevent the development of full-blown type 2 diabetes. Similarly, early detection of high blood pressure can lead to interventions that prevent heart disease or stroke.